Could be a Heavy 10 or bigger swing. Hard to tell from the picture.
You show the serial number which will allow finding the approx date of manufacture. The letters at the end confirm the swing, bed length etc.
This site has a lot of Southbend information.
http://www.wswells.com/sn/sn_index.html
Looks like the lathe was made in the early 1940's
http://www.wswells.com/photos/serial_no/SN_info_3.JPG
Also this site.
http://www.southbendlathe.com/older-machines/serial-numbers
Taking this apart is not difficult, but the pieces will still be heavy.
Greg Halligan took apart a similar style machine, his was 13in. He has a series of videos. This is the first. It shows the parts he removed to get the lathe into his basement.
Once you confirm the swing so know the lathe size, I would get a book on restoration of the model from EBay. Some idea of the process/large pieces.
You will need to cut the belt then can remove the head.
The motor can be removed, then the motor mount, then the louvered door.
Tailstock easy to remove, also the compound.
I would wind the carriage all the way to the right, then remove the screws to allow removing the saddle from the apron. Support the apron before doing this so you do not bend the feed screw. You can then remove the apron. You can then remove the Quick Change Gear Box along with the feed screw.
You will be able to remove the bed from the base and remove the chip pan.
I purchased my flat belt from this site. He has leather and nylon/rubber flat belts. I got the nylon/rubber. Works well.
https://albinoindustrialbelting.com/